Precipitation of dissolved solids from water is a result of the water reaching supersaturation, and many dissolved solids become less soluble at higher temperatures. Solids that behave in this manner are referred to as “inversely soluble”. The primary force inducing particle precipitation out of solution in water boilers is water temperature. Other parameters that contribute to particle precipitation include water hardness, conductivity, pH, water velocity, and alkalinity. These other parameters play a lesser role in boilers than they do in other systems due to the dramatic temperature increase. Of the many inversely soluble minerals that precipitate out of solution, the first is usually calcium carbonate. In untreated water, the initiation of particle precipitation is nucleation which occurs on surfaces of the boiler internal components, gradually producing an insulating scale that greatly reduces boiler efficiency.
To reduce or eliminate the build up of scale on boiler surfaces, a common practice is to treat the boiler water with water softeners to reduce the tendency for mineral precipitation and/or with other chemical agents to form compounds with increased solubility or other chemical complexes with the minerals dissolved in the boiler water to form precipitates in the boiler water, rather than on the boiler surfaces, which precipitates then settle by gravity to a low point of the boiler structure which then are periodically removed from the boiler, as by a “blowdown” procedure.
Another known way of causing precipitates to occur in the boiler water rather than on the boiler surfaces, is to treat the boiler water with oscillating electromagnetic flux, as for example with use of a device such as described in U.S. Pat. No. 6,063,267, owned by the Assignee of this application, which device is referred to as the “Dolphin” water treatment device and available from the Assignee of this application, namely Clearwater Systems, LLC of Essex, Conn., USA. Such exposure of the boiler water to oscillating electromagnetic flux causes nucleation of dissolved minerals to occur in the boiler water, which nucleation is then followed by an agglomeration of a nucleated particles into more massive and heavy precipitates which again settle by gravity to a low point in the boiler system and can be removed by periodic “blowdown” procedures.
The use of alternating electromagnetic flux for the treatment of boiler water has the advantage over chemical treatment of the water in that expensive chemicals and procedures and apparatus for adding the chemicals to the water are not required. On the other hand, both the chemical treatment and the treatment with a alternating electromagnetic flux have a common disadvantage in that the periodic boiler blowdowns required to remove the settled precipitates from the boiler system release significant amounts of hot water and therefore decrease the boiler efficiency.
A general aim of this invention is therefore to provide an apparatus for use with boiler systems to remove dissolved minerals from the boiler water before they form scale on boiler surfaces, which apparatus does not require the use of water softeners or other chemical agents and which apparatus greatly reduces the number of boiler blowdowns required over a given period of time.
In keeping with the above object, a further general object is to provide a water treatment apparatus for a boiler system which apparatus allows the boiler system to be operated continuously over long periods of time without blowdown and with a reduced need for manual supervision and maintenance.